Supporting the body with quality nutrition is one of the better things that you can do. Unfortunately in modern civilization, we are exposed to a diet that is largely chemical based. These mutations in the food supply leads to increased stress in the body, makes the immune system work harder and so on.
Real nutrition feeds the cells of the body which makes it stronger. I would avoid processed foods and get rid of artificial sweetners and as many chemicals as you can including cosmetics that have harmful chemicals, hair sprays, fluoridated toothpaste, shampoos with toxic chemicals and so on. Chemicals put a stress on the immune system and detoxification.
Considering that one might not know which pathogen is responsible for your illness then I would use natural herbs that have potential to kill a multitude of pathogens.
Things that come to mind are fresh, raw garlic, black seed, turmeric, neem, coconut oil. Drink chai tea which has a multitude of natural antibiotics such as black pepper, cardamom, ginger, black tea and others. Hemp oil (not marijuana) has antibiotic properties and may well help stabilize the nervous system. Colloidal Silver might be helpful as well since it can kill viruses and some bacteria.